Edge tools, for example for woodworking (e.g. woodturning tools), generally have to be sharp in order to obtain desired results. Sharpening may be performed by means of a rotating grindstone in a grinding machine.
An example of a conventional grinding machine 1 is shown in FIG. 1. The grinding machine 1 is provided with an essentially circular grindstone 2. The grindstone 2 is driven by a motor, e.g. an electrical motor (not shown), which is typically placed inside the grinding machine 1.
The grinding machine 1 is also provided with support means 3 in the vicinity of the grindstone 2. A purpose of the support means 3 is, as indicated in FIG. 1, to serve as a guiding means for an edge tool 4 to be sharpened by the grindstone 2.
In the exemplary grinding machine 1 shown in FIG. 1, the support means 3 is a cylindrical support bar, which is sometimes referred to as a universal bar. The cylindrical support bar 3 is essentially parallel with the rotation axis of the grindstone 2. Two cylindrical ends (or legs) 3′, 3″ of the cylindrical support bar 3 are to be inserted in respective holes 5′, 5″ of brackets 6 that are placed on top of the grinding machine 1. Typically, the cross-section of each hole 5′, 5″ is circular in order to achieve a desired radial play between the respective cylindrical ends 3′, 3″ and the respective holes 5′, 5″ when the cylindrical ends 3′, 3″ are inserted into the respective holes 5′, 5″. Furthermore, the position of the cylindrical support bar 3, and thus the distance between the cylindrical support bar 3 and the grindstone 2, may be adjusted to suit different needs or purposes for grinding different edge tools 4 by the grindstone 2. Said position of the cylindrical support bar 3 may e.g. be fixed by a set screw 7.
Typically, but not necessarily, a grinding jig 5 may be used in order to assist the user of the grinding machine 1 to hold the edge tool 4 correctly in relation to the grindstone 2 and on the cylindrical support bar 3. In order to set the position of the cylindrical support bar 3 for obtaining a desired edge angle of the tool 4 supported for grinding by the support bar 3, a tool setter as described in EP 1 818 138 B1 may also be advantageously used.
Furthermore, the grinding machine 1 may optionally comprise a wheel 9 for honing, as illustrated in FIG. 1.